Plant them as soon as you can, with twice the bulb's height of soil above them, and the leaves on the surface. Water them in well, and give them some liquid tomato food at the same time. Let the leaves die down naturally - don't cut or tie them - and remove them when they've gone brown, making sure that you fill the small hole left when you remove the leaf (leaving a hole will allow narcissus fly to get in and kill the bulb).

They should come up for you next year - mark their spot so you don't dig them up by accident.

In that case I think that your only real option is to pay someone to dig it out. Once that's done you could try covering the ground with a weed-proof membrane and covering that in turn with bark chippings - that would prevent any further germination and growth.

They need warmth to put up shoots, so you might like to move them somewhere warmer. However, March is a long time. Did you keep them moist? Or are they perhaps too wet? Have you planted them right way up, with the dip uppermost?